i0522-264 In-Duct Evaporative Cooling AD AW.qxp_HVR 114 x 306mm HP copy 20/06/2
www.heatingandventilating.net
“By adding an evaporative humidifier to an extract airstream, there is only a slight increase in overall energy consumption, whilst the energy recovery system’s potential for providing cooling in the summer is greatly improved.”
To put some figures against this potential, if the air extracted from the room is 21°C and 50%RH, and is humidified to 95%RH, a run-around energy recovery system with a 90% efficiency, could pre-cool incoming air of 28°C and 44%RH by up to 11°C. This level of cooling would significantly reduce a building’s HVAC energy consumption during the summer. It may not always replace the need for mechanical cooling, but it will greatly reduce the size of chiller needed and the ongoing energy consumption for mechanical cooling. This will lower a building’s carbon footprint and improve its sustainability. This type of evaporative cooling effect can be directly used on incoming supply
air too, but the cooling potential is limited by the humidity of the outside air and the allowable maximum humidity inside the building. By placing the humidifier on the exhaust airstream, rather than the incoming, the starting humidity condition is never that high. This allows for a good amount of evaporation and cooling to be achieved. And secondly, because the humidification is occurring on the extract air, there is no upper limit on the humidity level after the humidifier, so air can be taken right up to saturation point, with maximum cooling effect. For designers who want to know how much cooling would be available using
this exhaust air evaporative cooling strategy for a specific project, Condair offers an accurate calculator on the website
https://mycoolblue.com. It has worldwide weather data from over 300 locations and allows variable AHU configurations to be set. Accurate calculations are provided for the amount of exhaust air cooling that
will be delivered, alongside mechanical, in different climates and under different building operating conditions. For instance, a building in London with a room set point of 22°C, operating during office hours only, with a 3x3m evaporative humidifier and 3m/s airflow, could meet 55% of its annual cooling needs with exhaust air cooling. Whilst the same building in Syndey, Australia, would be able to achieve 36% of its cooling in the same way. As room conditions are relatively consistent in air-conditioned buildings
around the world, the strategy of exhaust air cooling is universal. Exhaust air evaporative cooling is a proven and effective strategy, and if more widely understood and applied, could help our industry take a further step towards its Net Zero goals.
Exhaust air
IN-DUCT EVAPORATIVE COOLING
When used in an AHU, the Condair ME delivers up to 800kW of cooling from less than 1kW of electricity.
Put Condair technology at the heart of your evaporative cooling strategy.
Condair ME Evaporative cooler Outside air
Evaporative cooler
Supply air
Return air
Contact us for free expert advice Tel: +44 (0)1903 850 200 Email:
uk.sales@
condair.com Web:
www.condair.co.uk
DOWNLOAD THE HVR APP NOW
Humidification, Dehumidification and Evaporative Cooling
July 2024 25
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